The answer to 'how much to replace smoke detector in Illinois' is that the cost to replace a smoke detector can vary widely depending on several factors. Typical ranges are usually between $50 to $200 per smoke detector, including parts and labor. The specific cost will depend on the type of smoke detector, whether it's hardwired or battery-powered, the complexity of the installation, and the labor rates in your local area.
It's best to get quotes from licensed and insured electricians in your local area, as they will be familiar with the local building codes and installation requirements. Many homeowners choose to have a professional electrician handle smoke detector replacements to ensure proper installation and compliance with safety standards.